Chang’e-6 collected soil from the Apollo Crater, located inside the enormous South Pole–Aitken Basin, a region known to have experienced repeated high-energy impacts for billions of years. Because the Moon has no atmosphere, no erosion, and no liquid water, it preserves ancient impact records extremely well. This makes lunar dust a perfect archive of early solar system bombardment.
The far side of the Moon is especially valuable because it is geologically different from the near side. It is older, less volcanic, and contains surface material untouched over long periods. That makes any unusual fragment found there particularly scientifically meaningful.
What Makes CI Chondrites Important
CI chondrites are among the most chemically primitive materials ever discovered — almost unchanged since the solar system formed 4.6 billion years ago. They are known for three defining features:
Extremely High Water Content
Up to 20% of their mass is water locked in hydrated minerals. This makes them some of the wettest objects in the solar system outside icy moons and comets.
High Organic and Volatile Content
They contain amino acid precursors, carbonates, magnetite, and other water-altered minerals, making them invaluable for studying prebiotic chemistry.
Primitive Composition Similar to Early Solar Nebula
Their elemental ratios closely match the Sun’s composition (minus volatile gases), indicating that CI chondrites preserve material from the earliest stages of planetary formation.
Because of these properties, CI meteorites are strong candidates for delivering water and organic molecules to early Earth.
Why These Meteorites Rarely Survive
Despite their importance, CI chondrites are extremely difficult to study because:
They are soft, brittle, and porous.
They disintegrate easily when passing through Earth’s atmosphere.
Impacts on planetary bodies often pulverize or vaporize them.
Less than 1% of all meteorites ever discovered belong to the CI group, making them the rarest carbonaceous chondrites on Earth.
Finding even microscopic remnants of these meteorites on the Moon is therefore extraordinary — and scientifically priceless.
How Chang’e-6 Scientists Identified the CI Fragments
A team led by geochemists Jintuan Wang and Zhiming Chen analyzed more than 5,000 microscopic grains from the Chang’e-6 samples.
They were especially searching for olivine, a magnesium-iron silicate common in both volcanic rock and meteorites. After isolating tiny “clasts” containing olivine, they polished, scanned, and chemically tested the fragments for clues about their origins.
Out of thousands of particles, they found seven olivine-bearing clasts whose properties matched no known lunar or terrestrial material. Instead, the particles showed features identical to CI chondrites.
Scientific Methods Used in the Analysis
Researchers used several advanced testing methods to determine the identity of the fragments:
Scanning Electron Microscopy (SEM)
Provided high-resolution imaging of the texture and surface details of each clast.
Electron Microprobe Analysis
Measured elemental composition, especially iron, manganese, nickel, and chromium.
Secondary Ion Mass Spectrometry (SIMS)
Examined isotopic ratios, including silicon and oxygen — crucial markers for determining origin.
These tools allowed scientists to determine the fragments’ chemical fingerprints with exceptional precision.
What the Chemical Testing Revealed
The seven fragments displayed:
Porphyritic textures: olivine crystals embedded in a glassy matrix.
Atypical iron-to-manganese ratios not found in lunar rocks.
Nickel and chromium oxide levels consistent with CI chondrites.
Oxygen and silicon isotopic signatures outside Earth-Moon ranges but inside CI meteorite boundaries.
The conclusion:
These clasts originated from a CI chondrite asteroid that impacted the Moon billions of years ago.
The impact melted the meteorite instantly — but cooled rapidly enough to preserve its original chemistry, allowing the fragile olivine fragments to survive in lunar soil.
Why This Discovery Could Explain Earth’s Water
One of the biggest mysteries in planetary science is:
How did Earth get its water?
Because Earth once experienced intense volcanic activity, atmospheric loss, and high temperatures, early surface water should have evaporated or escaped into space. This means water must have been delivered later by external bodies — likely asteroids.
CI chondrites are among the strongest candidates for delivering Earth’s water because:
They contain up to 20% hydrated minerals.
Their deuterium-to-hydrogen ratios match Earth’s ocean water.
They are rich in organic molecules needed for early life.
The confirmation that CI fragments reached the Moon suggests that the same types of asteroids also bombarded early Earth. Since Earth’s atmosphere destroys most fragile material, the Moon acts as a natural museum recording events that Earth cannot preserve.
This strengthens the theory that Earth’s oceans may have originated from hydrous asteroids similar to the one that left its mark on the Moon.
How Meteorite Impacts Shape Lunar and Earth History
Impacts are a major force in shaping both Moon and Earth histories. But while Earth continuously renews its surface through plate tectonics and erosion, the Moon remains mostly unchanged.
This means fragments preserved in lunar dust may record:
Ancient asteroid impacts
Changes in solar system material over time
Variations in water-rich body populations
Evidence of early solar nebula chemistry
The seven CI fragments discovered by Chang’e-6 are small, but they represent a monumental scientific jackpot.
What This Means for Future Space Research
Chang’e-6’s discovery opens up new avenues for future missions:
Targeting High-Impact Lunar Regions
The South Pole-Aitken Basin is now confirmed to store ancient and rare extraterrestrial materials.
Searching for Organic Molecules
If CI chondrite remnants survived on the Moon, traces of prebiotic organics may also exist.
Mapping Water Origins Across the Solar System
Future missions can compare lunar CI fragments with samples from Ryugu, Bennu, and other primitive asteroids to build a unified map of water delivery.
Strengthening International Collaboration
Understanding Earth’s water origins is a global scientific challenge. Data from China’s mission could support future joint lunar sample studies.
Key Data Table
Feature
CI Chondrites
Typical Lunar Rocks
Water Content
Up to 20%
Less than 1%
Porosity
Very high
Low
Organic Material
Rich in carbon compounds
Extremely low
Oxygen Isotopes
Match primitive solar material
Match Moon/Earth composition
Survivability in Atmosphere
Very poor
Not applicable
Frequency
< 1% of meteorites on Earth
Abundant on Moon
Final Thoughts
The Chang’e-6 mission has delivered one of the most significant lunar discoveries of the decade. For the first time in scientific history, confirmed CI chondrite fragments have been identified on the Moon. These tiny particles could hold answers to some of humanity’s biggest questions:
Where did Earth’s water come from? How did early life-forming ingredients reach our planet? What role did primitive asteroids play in shaping our world?
While much more research remains to be done, the discovery provides a powerful clue — one preserved in dust untouched for billions of years.
FAQ
What are CI chondrites?
These are rare, primitive meteorites rich in water and organic materials. They preserve some of the earliest chemical signatures from the solar system.
Why are CI chondrites important for understanding Earth’s water?
Their water content and hydrogen isotopic ratios closely match those of Earth’s oceans, making them strong candidates for delivering water during early planetary formation.
Why were CI fragments found on the Moon and not Earth?
Earth’s atmosphere destroys fragile meteorites. The Moon has no atmosphere and therefore preserves ancient impact materials much better.
How old are the CI fragments found by Chang’e-6?
They likely originate from impacts billions of years ago when the solar system was still experiencing heavy bombardment.
What are the next steps for researchers?
Scientists will compare these lunar fragments with asteroid samples from missions like Hayabusa2 and OSIRIS-REx to better understand planetary water delivery.